The New York hotel scenes are all filmed at Stoneleigh Abbey and the bridal suite is actually a room Queen Victoria stayed in, in 1858 at Stoneleigh Abbey.
The children dancing on the boat wearing Hawaiian themed outfits are Youth Creation, finalists from Britain's Got Talent (2007) 2013.
When Mr Poppy and Mr Shepard are re-enacting the proposal scene, the name of the boat is 'Catherine'. The character who Mr Shepard is proposing to, Sophie, is played by 'Catherine Tate'.
The chief Elf (Simon Lipkin) plays Mr. Poppy's brother in Nativity Rocks